粗苯精餾過程的模擬計算-

1、收稿日期:2002-12-08作者簡介:張艷輝,女,講師,碩士,主要從事化學(xué)工程與工藝方面的研究,聯(lián)系電話:0351-*粗苯精餾過程的模擬計算張艷輝1王志鋒2劉有智3(1、3.山西太原華北工學(xué)院化學(xué)工程系030051;2.山西太原中科院山西煤炭化學(xué)研究所030051摘要以汽液平衡為基礎(chǔ),應(yīng)用精餾原理建立了粗苯精餾的數(shù)學(xué)模型,并采用三對角矩陣法、高斯消元法和追趕法對模型進(jìn)行了模擬計算。通過驗證,證明了該模型是可靠的,通用的,從而為確定精餾塔的設(shè)計或操作方案提供了定量依據(jù)。關(guān)鍵詞粗苯精餾汽液平衡模擬計算中圖分類號T Q0241.1+1文獻(xiàn)標(biāo)識碼A 文章編號1003-6490(200301-00-0

2、40引言煤焦化后的煤氣經(jīng)過抽提可獲得粗苯。粗苯中含有苯,甲苯,二甲苯,尤其是苯的含量較高,因此在苯的生產(chǎn)中,焦化苯所占比重較大。在粗苯的分離法中,結(jié)晶法比較經(jīng)典,但噻吩和苯易生成混合結(jié)晶。而萃取法因其裝置規(guī)模小,處理原料的非芳烴含量低,應(yīng)用不十分廣泛。從綜合利用的角度出發(fā),工業(yè)生產(chǎn)中經(jīng)常利用粗苯組分的相對揮發(fā)度大的特點而采用精餾法分離粗苯。為了便于在生產(chǎn)中分析過程,標(biāo)定數(shù)據(jù),制定合適的設(shè)計操作方案,提高設(shè)備的生產(chǎn)能力和產(chǎn)品質(zhì)量,本文對粗苯精餾過程進(jìn)行了模擬計算。1數(shù)學(xué)模型的建立1.1模型塔由于實際生產(chǎn)中操作方案的多樣性,在建立粗苯精餾分離過程的數(shù)學(xué)模型時,應(yīng)先設(shè)計一個廣泛適用的模型精餾塔,如圖

3、1所示 。圖1模型精餾塔該塔具有任意板數(shù),可在任意板上設(shè)置進(jìn)料口、側(cè)線汽液相出料口及換熱設(shè)備。1.2模型方程組第29卷第1期2003年3月化工設(shè)計通訊Chemical Engineering Design C ommunicationsV ol.29N o.1Mar.2003根據(jù)精餾原理對模型進(jìn)行物料衡算和熱量衡算得到如下方程:1相平衡方程y i ,j =K i ,j x i ,j 1i C 1j N (12各組分的物料平衡方程第1塊板(冷凝器V 2y 1,2-V 1y i ,1-(S 1+L 1x i ,l =0(2第j 塊板(2j N -1F j z i ,j +L j -i x i ,j

4、 +V j +1y i ,j +1-(L j +S j x i ,j-(V j +G j y i ,j =0(3第N 塊板(再沸器L N -1x i ,N -1-(V N +G N y i ,N -L N x i ,N =0(43熱平衡方程第1塊板(冷凝器V 2H V2-V 1H V 1-(L 1+S 1H L 1-Q 1(5第j 塊板(2j N -1V j +1H VJ +1+jk -2F kHF k+jk -2Qk-Q 1-I j H Lj -jk -2S k HL k-jk -2G k H k -j k -2G k H Vk -V 1H V1=0(6第N 塊板(再沸器L N -1H LN

5、 -1+Q N -(V N +G N H V N -L N H LN =0(74分子分?jǐn)?shù)加和式Ci =1x i ,j -1=01j NCi =1y i ,j -1=01j N(82數(shù)學(xué)模型的計算多參數(shù)SH BWR 狀態(tài)方程同時適用于汽液相,可以較準(zhǔn)確地反映烴類及其混合物的熱力學(xué)數(shù)據(jù)。在混合規(guī)則的基礎(chǔ)上,利用此方程確定汽液相的密度、逸度及焓等參數(shù)4。2.1各板組成的計算消元后的式(1(4組成了M -K 方程組,對i 組分M -K 方程組可表示為以下三對角矩陣形式:B 1C 1A 2B 2C 2x 2D 2A jB jC jMA N -1 B N -1C N -1A NB Nx 1x 2Mx j

6、M x N -1x ND 1D 2M D j MD N -1D N含有c 個組分的系統(tǒng)可寫出c 個三對角矩陣,然后運用高斯消去法1消去x j -1,再利用追趕法2求出液相組成x i ,j ,汽相組成y i ,j 通過調(diào)整平衡常數(shù)得到。2.2熱負(fù)荷的計算將利用SH BWR 狀態(tài)方程求得的汽液相的焓回歸成以下形式:H 01=B 0i +B 1i T100+B 2i T1002+B 3i T1003+B 4i 100T(10把回歸焓值和調(diào)整的汽液流量代入方程(5(7,即可求得再沸器、冷凝器及各板的熱負(fù)荷。2.3計算程序的編制58由于計算中部分變量既關(guān)于組分又關(guān)于塔板,所以采用二維數(shù)組來表示。對于逐板

7、計算,用循環(huán)來實現(xiàn),如圖2中的K 循環(huán)和V 循環(huán)。算法中涉及到眾多既前后聯(lián)系又相對獨立的變量和計算式,因此采用函數(shù)更方便。程序框圖如下:3數(shù)學(xué)模型的驗證程序中塔板數(shù)是宏定義,可以任意設(shè)定進(jìn)料量、出料量、塔板壓力、回流比等?，F(xiàn)將文獻(xiàn)2提供的數(shù)據(jù)輸入計算程序后,獲得了數(shù)學(xué)模型的計算結(jié)果。為了檢驗?zāi)Ｐ偷暮侠硇?適用性,將模型的計算結(jié)果與文獻(xiàn)3中的實驗值進(jìn)行比較,結(jié)果如表1所示。由表1可以看出,除了塔底苯組成和塔頂二甲苯組成的偏差大于0.001以外,其余均小于0.001,所以模型適合于粗苯精餾。4結(jié)論25化工設(shè)計通訊第29卷表1粗苯精餾的數(shù)模與實驗結(jié)果的比較塔頂產(chǎn)品組成苯甲苯二甲苯塔底產(chǎn)品組成苯甲苯二

8、甲苯冷凝熱負(fù)荷,k J再沸器熱負(fù)荷,k J實驗值0.960.040.000.0020.3360.662355183528107.9計算值0.9598310.0399860.0017890.0019970.03357830.661442354923.4527838.7相對偏差%0.0170.0350.180.150.0780.0840.0730. 051圖2計算程序框圖本文通過對焦化粗苯精餾過程的模擬計算,可得出如下結(jié)論:a.數(shù)模檢驗結(jié)果表明,模型具有可靠性及適用性;b.依據(jù)通用的模型塔,利用嚴(yán)格法建立數(shù)學(xué)模型,可解決烴類系統(tǒng)的多元精餾問題,說明模型具有通用性;c.模型模擬了粗苯精餾時的傳質(zhì)、傳

9、熱情況,為確定精餾塔的設(shè)計或操作方案提供了定量依據(jù)。C組分?jǐn)?shù);F進(jìn)料流率,km ol/h;G側(cè)線氣相出料流率,km ol/h;H焓,kcal/km ol;K相平衡常數(shù);x液相組分摩爾分率;L下降液體流率,km ol/h;N塔板數(shù);下標(biāo)l冷凝器;i某一組分;j某一塔板;F進(jìn)料;N再沸器;Q傳熱速率,kcal/h;S側(cè)線液相出料流率,km ol/h;T溫度,K;V上升蒸汽流率,km ol/h;y汽相組分摩爾分率;L塔內(nèi)液相;V塔內(nèi)汽相;0理想狀態(tài)。參考文獻(xiàn)1張吉瑞.化工數(shù)值方法.北京:中國石化出版社,19952沈春謹(jǐn).處理量5000t/a粗苯精餾裝置學(xué)士畢業(yè)論文.太原機(jī)械學(xué)院,19863王葳,魏奇

10、業(yè),高維平.多組分精餾塔靈敏度系數(shù)及靈敏度的計算.計算機(jī)與應(yīng)用化學(xué),1999(2:1331394金克新,趙傳鈞,馬沛生.化工熱力學(xué).天津:天津大學(xué)出版社, 1990:1281375周愛月編.化工數(shù)學(xué).北京:化學(xué)工業(yè)出版社,1993:3804206R obert W.H ornbeck美著.劉元久譯.數(shù)值方法.北京:中國鐵道出版社,1982:2002807W.L.盧伊本著.張竹治,王開正譯.化學(xué)工程師使用的過程模擬化,模擬和控制.北京:原子能出版社,1987:1502008W.H.Press,S.A.T eukolsky美著.傅祖云,趙梅娜,丁巖譯.C 語言數(shù)值算法程序大全.北京:電子工業(yè)出版社

11、,1995:69971635第1期張?zhí)蚁?粗苯精餾過程的模擬計算Zhejiang Zeguo Chemical Machine Works,Weiling,317523 Abstract:D ouble-roller com m inutor can be used to produce com2 pound fertilizer.N o drying is needed,besides,production can be conductedunder ambient tem perature.T he process design in reas onable,the techn ology

12、is feasible.key w ord:double-roller comminutor,design,applicationBursting P ressure P rediction of MultilayeredCylinder&Spherical ShellsX iao Lihua1,Liu X iaoning2(1.Changde Vocational Univer sity,Hunan Changde,415900;2.Wuhan Vocational Univer sity o f Industry&T ra ffic,Wuhan,430015Abstract:In this

13、 article,the in fluence of thickness reduction due to big deform ation for bursting pressure of multilayered cylinder&sphericalshells is analyzed.T he formula of bursting pressure is found.W ith E x peri2m ents count verification,the distinguishing feature of this formula sh ow,formsim ple,caculatio

14、n convenience,high precision,fluctuation scope sm all andstable is g ood.T he results is provided reference for techn ology design using.key w ord:multilayered,cylinder&spherical shells,bursting pressure,caculation formula.C alculation of Diagonal R ound W eakening Coefficient of H oleR einforcem en

15、t on P ressure V esselLi Bingrong(Hunan Chemical Research Institute,Changsha,410007Abstract:T his article describes tw o calculation meth ods for diag onal round weakening coefficient of h olerein forcement on pressure vessel by means of definite in2tegral and inequality principles,i.e.accurate calc

16、ula2tion and approximate calculation.key w ord:hole reinforcem ent,diagonal round w eakening coefficient,calculationDiscussion of R elationship B etw een Function and Aesthetics ofI ndustrial Buildings T ake H unan Biologically Ph arm aceuticalF actory R elocation P roject for E xampleR ao X u an(Hu

17、nan chemical&Pharmaceutical Engineering DesignInstitute,Changsha,410007Abstract:Industrial building design must meet the requirement of function at first,then y ou must considerthe organic com position of function,environment,land2scape and aesthetics.key w ords:industrial building,function,aesthet2

18、 ics,h omm izationComp arison of N ew and old Design codes for Oil refuelling Station and Application in P racticeW en WuAbstract:It com pares s ome clauses in new and old de2 sign codes for oil refuelling station,besides,it puts theminto practice.key w ards:oil refuelling station,code,com pari2 s o

19、n,applicationT reatment of W aste G as Discharged by CS2plantU sing E letric Furnace ProcessYin Xianqi(Zhuzhou Bene ficiation Reagent Factory,Zhuzhou,412005Abstract:This article describes the principle and process of treatment of waste gas discharged by CS2plant using electric furnace process.It de2

20、 velops a new way for H2S reuse.It has g ood econom ic and s ocial benefits.key w ords:CS2,amm onium sulfide,H2S purificationA nalog computation of CrudeB enzeneR ecti fication ProcessZh ang Yanhui1,W ang Zhifeng2,Liu Youzhi3(1、3.Chemical Engineering Department o f North ChinaEngineering College,Tai

21、yuan,030051;2.Shanxi CoalChemical Research Instiute o f Chinese Academy o fSciences,Taiyuan,030051Abstract:This article establishes a mathematical m odel for crude benzene rectification by use of rectification principle on the basis of vapor2 liquid balance.Besides,it makes analog com putation for t

22、he m odel by use of triple diag onal matrix method,G aussian elim ination method and pursuit method.Result proves that this m odel is reliable and universal.This m odel will provide a quantative basis for the design or operating scheme determ ina2 tion of rectification tower.key w ords:crude benzene

23、,rectification,vapor2liquid balance,analog com putationDirect Method of C alculating the Q uantity of F luid P assingthrough a Pipe and calculating the diameter of a pipeH ong Liang,Zh ang T aoxian,Sun R ong,Liu Xiaoning(Wuhan technical college o f industry andtransportation,Wuhan,430015Abstract:Up

24、to now,calculating the quantity of fluid flowing throughthe pipe still depends on trial-calculating method,through,this kind ofmethod is inconvenient.Through analyzing,the authors of this paper con2sider it possible to calculate these quantities directly by adopting a newRe22Re andRe22Re calculation

25、 chart,through which a direct method ofs olving this s ort of problem can be acquired.This new method shares theadvantage of convenient and can supply a reference to the people inv olved inenqineering design.key w ords:pipe calculation of flowing fluid quantity,trial2calculating method,direct method,new calcula2tion c